The need for the development of new strategies for treatment of cardiac arrhythmias, including ventricular arrhythmias, has experienced a palpable increase in the last few years. Ventricular Arrhythmia (VA) or ventricular tachycardia (VT) is a severe abnormal heart rhythm which can cause death if not treated immediately. Ventricular Fibrillation (VF) is the most serious form of VA. VF is most commonly caused by VT and is responsible for 75-85% of sudden cardiac deaths (SCD). While several treatment options are currently in use/under investigation, many if not all remain suboptimal. This is critical as it is estimated that SCD is responsible for ~450,000 deaths in the US annually. While various treatment options currently exist, a number of issues have been reported including the high cost of treatment, patient discomfort, organ toxicity and incomplete treatment among others. As such there is an ever growing urgency and compelling need for the development of new strategies and devices to treat VT. The intent of this project is to develop and characterize a new endovascular based endocardial cryoablation treatment strategy and catheter system (ICEolate) for the treatment of VT. This technology will enable the focal (spot) as well as linear ablation lesions and have the capability of conducting electrical activity mapping, including cryomapping, of cardiac tissue prior to and following ablation. Additionally, the technology will be used in conjunction with transesophageal echocardiogram imaging which will enable direct visualization of lesion formation. The prototype unit and preliminary data collected to date strongly support the potential of this approach. The major goals of this Phase 1 proposal are to (1) develop the ICEolate catheter (2) test this new treatment protocol in an ex vivo tissue model, and (3) conduct a pilot in vivo study to validate development. The successful completion of this project will lead to a new minimally invasive endovascular based approach for the management of VT and other cardiac arrhythmias. Further, this project will provide data in support of establishing dose parameters necessary for optimal clinical application for the treatment of cardiac arrhythmias. Once completed, this project will provide for an effective, minimally invasive treatment option for individuals suffering from VT, contributing to efforts for improving patient survival and quality of life.